Power supply for anodising?

[Zeeflyboy]

Hi guys,

I've been doing my research on anodising and while there are some guides on cobbled together systems using lead acid chargers and dimmer switches, it seems like the message is that the most important part for consistent results at home is using a good constant current power supply.

However, the amperage requirement for reasonable sized parts (around 2-3ft^2 in my case) makes it quite hard to find a reasonably priced supply and I don't seem to see many recommendations in all the various blogs/forum posts.

To that end, just wondering if anyone had come across a supply they could recommend? Using the LCD method described by caldwell, it seems they talk about 4.5amps per sq ft so really I'd be looking at a supply capable of around 20 amps

I did come across this, which might be suitable... while its not crazy expensive it's not pocket change either and I really have no idea if this is the sort of supply I need. https://www.reichelt.com/gb/en/?LANG...MaAkl2EALw_wcB


Alternatively I have a rather powerful PSU that I bought a while back to use for my RC charger, capable of 2000w and 12v or 24v output. I believe it is basically two pc power supplies combined, but of course I would need some way to turn that into a constant current system... and I'm largely an electrical dunce. would my rc charger (two 500w outputs, can do lead acid up to 24v in the options) be suitable or is the clever charge circuitry going to get in the way?

Any advice would be gratefully received!

[Zeeflyboy]

alternatively, this one is a bit cheaper...

15v should be sufficient? Allows up to 6amps/sqft according to the 720 calcs.... any thoughts on whether it is desirable to be able to do more than that?

https://www.reichelt.com/gb/en/?LANG...QaAlKfEALw_wcB

[m_c]

Something like what you've linked looks good.

Alternatively, have a search over on the EEVblog forum, as I'm sure I've read some posts on there about constant current supplies (I've not been on there for a good while, so I may be getting confused with somewhere else!).
I'm sure there's plenty constant current schematics around, but when you get to that amount of current, they have to be well designed to avoid releasing magic smoke.

[Zeeflyboy]

Thanks for that, I'll have a look over there but since you say one of those I linked is suitable I will probably go for a proper retail unit rather than try building my own.

Cheers

[Jonathan]

One of these:

https://www.aliexpress.com/store/pro...22388c28Yvk2a1

With a suitable transformer - or batteries if you want.

Housed in a case, if you want ...

[Boyan Silyavski]

I was in that doubt before some time.

Maas HCS 3400 1-15V, 0-40A Bench Power Supply was the one i bought and i believe is a best heavy duty budget one that could cover quite big parts like alloy wheels and so on. Its well tested and serves for the purpose, German quality control , its Chinese but bit better than no name crap.

[Zeeflyboy]

The current dropping off is doing a constant voltage technique though no? You seem to be describing constant voltage but with a limit on the current.

My understanding is that the constant current technique tries to maintain whatever current you have set by raising the voltage. So one takes the sq ft of the part, multiply by 6 (if using 6asf) and then set that result in the power supply, which will then slowly raise the voltage as necessary to maintain that current. Using the 720 calculator you can then determine that at 6asf for example, the final voltage will be 15v and it will take 2hrs for a 1mil layer.

Thanks for all the tips - I believe I should be using a polypropylene tank, my slight problem is that my larger parts are quite long. I found a suitable polypropylene container in home base, but to get enough length its a 60L tub, which is a lot of acid, heavy and a big thing to store when it's far wider than needed in reality. I could get away with something much thinner, but never seen anything suitable and not sure how I would go about building my own tank.

Would a fish tank work? You can get those fairly long and thin, but not sure about the sealant they use and the acid.

[Clive S]

If it is only for one long part you could use some heavy duty membrane (think dpc under concrete) and make a temp. trough with timber to support it (outside of course). Or dig a channel in the garden to support it

[Boyan Silyavski]

Long pipe cut along in half ? like the ones they use now for drainage or water, they are from some heavy duty PP or PE. Any construction site will have pieces thrown

[Zeeflyboy]

Decided just to buy an 80L polypropylene crate.... Internal dimensions are about 600x400x400ish mm so will fit the longest parts I currently plan to use and means I can do batches of smaller parts to save time.

It's wider than I needed, but I have designed a little PVC pipe cooling system which will eat up some of the volume... will just run cold water through it to keep the tub cool. Whether or not it's necessary really, probably not, but at least it takes a few litres of displacement out of the tank which is a few less litres of acid to deal with!

Cheers for the assistance chaps